Drying method

ABSTRACT

An apparatus for and method of drying articles such as tubular containers each having a bottom wall, an adjoining side wall, and an open end wherein said containers are supported in an inverted position and a drying gas moved therepast in such a manner that it circulates around and within the containers and provides efficient drying of both the interiors and exteriors thereof.

United States Patent Lee, Jr. 1 Apr. 10, 1973 {5 1 DRYING METHOD 3.0%.l62 7/1963 .Iepson .34 33 3,262,460 7 19(6 H dd] al. ..l34 Ill X [751 Richmmd, 3,381.39! simels Y:nglfa;i\ (14/105 [73] Assignee: The Reynolds Metals Company,

Richmond.Va. C H D0 J Primary Examiner arro B. rity, r. [22] Flled: 1971 Attorney-Glenn, Palmer, Lyne, Gibbs & Thompson {21] Appl. No.: 106,904

Related US. Application Data 57] ABSTRACT [62] givision of Ser No. 8l8,2l5, April 22, 1969, Pat. An apparatus for and method of y g articles such as tubular containers each having a bottom wall, an adjoining side wall, and an open end wherein said con- [52] US. Cl. ..34/2l3,5;/2353,l33g/1l0552, miners are Supported in an inverted position and a drying gas moved therepast in such a manner that it [51] Int. Cl ..F26b 7/00 58 M Se h 34/21 33 104 34 circulates around and within the containers and pro- 1 o arc vides efficient drying of both the interiors and exteri 34/105, 225; 134/70, 72, I52 ors thereof [56] References Cited 7 Claims, 6 Drawing Flgures UNITED STATES PATENTS 2/l954 Drum et a]. ..34/2l PATENTEU 3.726.U2U

SHEET 1 [IF 2 INVENTOR HARRY W. LEE, JR.

dubbg o jkmpocyw) HIS ATTORNEYS DRYING METHOD CROSS REFERENCE TO RELATED APPLICATION This application is a divisional patent application of its co-pending parent application, Ser. No. 818,215, filed Apr. 22, 1969, now US. Pat. No. 3,574,952 issued Apr. 13, i971, and is assigned to the same assignee to whom the parent application is assigned.

BACKGROUND OF THE INVENTION Many apparatus and methods have been proposed heretofore for drying tubular containers, such as cans each having one open end, for example, by passing a drying gas thereover. However, such previously proposed apparatus and methods do not provide efficient drying of the interiors of such cans because of their inability to circulate the drying gas inside each can.

SUMMARY This invention provides an improved apparatus for and method of drying articles such as tubular containers each having a bottom wall, an adjoining side wall, and an open end wherein said containers are sup ported in an inverted position and a drying gas circulated therepast in such a manner as to provide efficient drying of the exteriors thereof while simultaneously providing circulation of such drying gas within each container to also provide efficient drying of the interiors thereof.

Other details, uses, and advantages of this invention will become apparent as the following description of the exemplary embodiment thereof presented in the ac companying drawings proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show a present exemplary embodiment of this invention, in which FIG. 1 is a perspective view with parts broken away illustrating one exemplary embodiment of the apparatus of this invention used to dry tubular containers each having only one open end;

FIG. 2 is a view taken essentially on the line 2-2 of FIG. 1;

FIG. 3 is a greatly enlarged fragmentary perspective view of a portion of the conveyor comprising the apparatus of FIG. 1;

FIG. 4 is a side elevation with parts broken away of the apparatus of FIG. I particularly highlighting the method utilized to circulate a drying gas over the containers;

FIG. 5 is a greatly enlarged fragmentary view taken essentially on the line 5-5 of FIG. 4; and

FIG. 6 is a greatly enlarged fragmentary view with an exaggerated spacing between containers particularly illustrating the manner in which a drying gas is circulated past a plurality of inverted containers to provide rapid and efficient drying of both the interiors and exteriors thereof while providing circulation of gas within each inverted container.

DESCRIPTION OF ILLUSTRATED EMBODIMENT Reference is now made to FlGS. 13 of the drawings which illustrate one exemplary embodiment of the apparatus and method of this invention which is designated generally by the reference numeral 20. The apparatus 20 comprises an endless chain conveyor 21 which has a maximum open area which allows substantially unobstructed flow therethrough of a drying gas in a direction perpendicular to its supporting surface. The conveyor 21 has a horizontally extending portion 22 which is adapted to support a plurality of elongated tubular articles shown as a plurality of tubular containers or cans 23 each having a bottom wall 24 and an adjoining side wall 25 terminating in an end edge 26 defining an open end, see FIG. 6.

The cans 23 are supported on the horizontally extending portion 22 of the conveyor 21 with their axes arranged vertically and in parallel relation. A system is provided for circulating a drying gas or fluid, heated air in this example of the invention, around the cans 23 so as to provide efficient simultaneous drying of both the interiors and exteriors of such cans.

The apparatus 20 has means for directing the drying air, indicated in the drawings by a plurality of arrows 30, so that the air is directed toward the cans 23 at high velocity and in a plurality of closely spaced jets, with the spacing between such jets assuring that at least one jet is directed normally toward each of the cans 23 and in particular substantially toward the central portion of the bottom wall 24 of each can 23. The apparatus 20 has means for dampening any turbulence in the heated air as it approaches the cans 23 and in this example of the invention the dampening means comprises a plurality of sets 31 of screen and plate assemblies arranged parallel to the horizontal portion 22 of the conveyor 21 and with each set being defined by a perforated plate 32 adjoined by a screen 33 arranged upstream thereof. The apparatus 20 also has a planar sheet 34 which has a plurality of spaced openings 35 provided therein and the openings 35 define the previously mentioned jets which assure that heated air is directed toward the cans 23 at high velocity.

The apparatus 20 also has a flow control device arranged beneath the horizontal portion 22 of conveyor 21 which is used to create a negative pressure beneath the conveyor and cans 23 and in this example of the invention such flow control device comprises a plate 36 having a plurality of apertures 37 therein. The plate 36 with its apertures 37 operates to restrict air flow in a controlled manner creating a venturi effect which causes heated air to circulate inside the inverted cans 23 and provide an efficient drying of the can interiors. It will also be appreciated that the construction of the conveyor 21 may be such that it cooperates with the plate 36 to provide controlled flow producing the above-mentioned venturi effect.

The apparatus 20 has what will be referred to as a drying chamber 40 defined by a housing 41 which has openings 42 and 43 at opposite ends thereof which allow the conveyor 21 with the cans 23 supported thereon in an inverted manner to pass through the chamber 40 in a continuous manner to enable high speed drying thereof. The housing portion 41 and hence drying chamber 40 is supported on an associated supporting floor by a plurality of spaced vertical legs 44.

The apparatus 20 also includes a duct assembly 45 arranged beneath the housing portion 41 and the assembly 45 has an upstream end fastened in sealed relation to the housing portion 41 and a downstream end fastened in sealed relation to the inlet of a centrifugal fan 46. The apparatus 20 also has a duct assembly 48 which includes a vertically extending portion 50 which is fastened in sealed relation to the discharge of the fan 46, a vertical downwardly flaring frusto-pyramidal section 51 fastened in sealed relation to the top portion of the housing 41 and a substantially U-shaped transition section 52 connecting the vertical sections 50 and 51.

The fan 46 has a shaft 53 extending therefrom which is supported by a pair of antifriction bearings 54 carried on a support 55 and the shaft 53 is driven by a suitable drive motor 56. The apparatus 20 has a plurality of heaters 57 which may be in the form of electrical heaters which are provided with electrical power from any suitable power source and are utilized to heat the air which is used to dry the cans 23.

As will be apparent particularly from FIG. 4 of the drawings, the air circulating system for the apparatus 20 comprises a closed loop system which circulates heated air past the containers 23 in the drying chamber 40. The air is then recirculated past the heaters 57 to remove any moisture that may be present therein. In addition, suitable air temperature control devices may be arranged downstream of the heaters 57 and used to control such heaters and hence the temperature of the heated air to provide optimum drying efficiency.

The cans 23 which are to be dried are moved from a can washer, for example, in an inverted position and placed on the horizontally extending portion 22 of the conveyor 21 so that they may be moved through the drying chamber 40. Any suitable technique may be utilized to place the cans 23 on the conveyor 22 such as by manual or automatic means. For example, an endless conveyor 60 may be used to move washed cans from a can washer 61, see FIG. 2, to a transfer mechanism such as a horizontally reciprocating plate assembly 62 which transfers the cans onto the horizontal portion 22 of the conveyor 21. It will also be appreciated that the conveyor 21 may also be provided so that the horizontally arranged portion 22 extends completely through the washer thus eliminating the need to provide a separate conveyor from the washer 61 and a device to transfer the cans from the washer conveyor to the conveyor 21.

As the cans 23 are moved through the drying chamber 40 the high velocity jets of air defined by the openings 35 in the sheet 34 impinge downwardly against the bottom walls 24 of the cans 23 while sweeping past the side walls 25 at a sufficiently high velocity to provide efficient transfer of heat to and hence drying of the side walls. As the air sweeps past the cans 23, the plate 36 with its apertures 37 helps control the air flow and causes a negative pressure in a chamber 63 defined beneath the plate 36 so as to provide the previously mentioned venturi effect causing circulation of the heated air within each can 23 and as indicated in a somewhat exaggerated manner by the arrows 64 and 65 in FIG. 6 of the drawings.

Thus, it will be seen that the high velocity heated air bathes the outside of each can 23 while the components of the apparatus 20 cooperate to provide circulation of heated air within each can 23 whereby efficient drying of both the interiors and exteriors of the cans 23 is provided. In addition, the air flow is such that the cans 23 are maintained in their upright positions as they pass through the drying chamber 40.

The conveyor 21 comprising the apparatus 20 has been described as a chain conveyor having a maximum open area which enables substantially unobstructed air flow therethrough. The conveyor 21 comprises a plurality of links 66 each having an undulating configuration essentially as shown in FIG. 3 with each pair of adjoining links being held together by an elongated rod 67 which may extend across the full width of the conveyor 21. The individual links 66 and their rods 67 may be made of any suitable corrosion resistant material such as stainless steel or a plastic material. Yet, the construction of the conveyor 21 is such that it may be moved in a continuous endless path.

The conveyor 21 is supported by a plurality of toothed rollers 68 which have cooperating teeth which are received within openings 70 defined between adjacent chain links 66. One of the rollers 68, shown as the upper left hand roller in FIG. 2 and indicated at '71 is driven by a suitable drive motor to enable movement of the conveyor 21 in an endless path.

The plate 36 with its apertures or openings 37 is supported beneath the horizontal portion 22 of the conveyor 21 in any suitable manner. However, in this example of the invention the plate 36 is in the form of a support plate which is suitably fixed to the legs 44 and has a top surface which supports the horizontal portion 22 for sliding movement thereacross with minimum frictional drag while assuring that each can 23 is supported on its associated end edge 26 with optimum stability.

To minimize the frictional drag between the conveyor and the plate the conveyor 21 and/or plate 36 may have their rubbing surface portions either made of or treated with suitable antifriction materials. In addition, elongated narrow strips made of an antifriction material may be fixed on the plate 36 to reduce the rubbing area.

As previously mentioned a plurality of dampening assemblies 31 is provided for dampening any turbulence in the heated air as it approaches the cans 23 and each dampening assembly is comprised of a plate 32 adjoined by a screen 33. Each plate 32 preferably has a plurality of openings 72 provided therein while each screen 33 is in the form of a large mesh screen defined by a plurality of crisscrossed undulating wires 73 which, due to the undulating character thereof, help minimize any turbulence in the flow of heated air as it approaches the planar sheet 34 and thereby assures the provision of uniformly spaced high velocity jets of air exiting the lower surface of the plate 34 toward the cans 23, see FIG. 4.

As will be apparent from FIG. 6 of the drawings, each bottom wall 24 of each exemplary can 23 has an outwardly concave recess or depression 74 defined therein and with the cans moving into the drying apparatus 20 from an associated washer in an inverted position washing fluid, such as water, for example, is contained in each depression 74. However, the area of each opening 35 and the spacing between openings is correlated with the diameter of the cans 23 to assure that at least one jet of heated air is directed substantially normally, i.e., perpendicularly, toward the bottom wall 24 of each can 23. Thus, with the presence of a washing fluid, such as water, within a depression 74 it will be seen that the jet of air impinging thereagainst displaces the washing fluid from within the depression and downwardly along the associated side wall whereupon the high velocity heated air provides rapid drying of the bottom wall 24 and side wall 25.

As previously indicated, the cooperating arrangement of the openings in sheet 34 and the apertures 37 in the plate 36 together with the circulation of heated air as provided by the fan 46 results in the provision of a positive pressure ranging roughly between one-fourth and one-half inch of water in the drying chamber 40 immediately above the sheet 34 whereby a negative pressure ranging roughly between one-half inch and 2 inches of water is provided in the chamber 63 immediately beneath plate 36. This pressure distribution and the cooperating arrangement of components is such that the cans 23 are maintained in a sta ble upright manner, yet an efficient drying is provided by air flowing inside of and around such cans.

The sheet or plate 34 is positioned a controlled distance above the bottom walls 24 of the cans 23 and as indicated at 75 in FIG. 6. Suitable means may be provided in the housing 41 to assure that the sheet 34 may be moved to accommodate cans of different heights and thereby assure impingement of air at high velocity against the bottom walls of the cans 23 as well as high velocity flow along the side walls of such cans. It will also be appreciated that with the apparatus and method of this invention the cans 23 may be packed tightly with their side walls 23 substantially in adjoining relation during movement thereof by the conveyor 21 through the drying chamber 40. With the cans tightly packed there is less area between adjacent cans which causes higher velocity air flow along the side walls of the cans 23 whereby more efficient heat transfer is provided and hence more rapid and efficient drying of the particular cans. in particular, using the standard 12 fluid oz. beverage can of circular cross-sectional con figuration the effective area between cans is roughly 10 percent of the total available supporting area of the horizontal portion 22 of belt 21 which is within the chamber 40, for example. This 10 percent area assures high velocity flow and efficient heat transfer.

The presentation of FIG. 6 has been made with the cans 23 arranged in widely spaced relation to demonstrate the action that takes place whereby air is circulated at high velocity around the exteriors of the cans and within the inverted cans to provide efficient high speed drying. An efficient high speed drying action takes place which is made possible by both convection and conduction and irrespective of whether the cans are widely spaced as much as or more than shown in FIG. 6 or are packed tightly together.

While a present exemplary embodiment of this invention, and method of practicing the same, has been illustrated and described, it will be recognized that this invention may be otherwise variously embodied and practiced by those skilled in the art.

What is claimed is:

l. A method of simultaneously drying both the inside and outside of tubular containers each having a bottom wall and an adjoining side wall terminating in an end edge defining an open end; said method comprising the steps of; placing each of said containers in an inverted manner with its end edge resting on a horizontal portion of a perforated conveyor having a supporting surface and which allows substantially unobstructed flow of a drying gas therethrough in a direction perpendicular to its supporting surface; supporting a control device for said drying gas beneath said horizontal portion; said control device having a plurality of spaced apertures therein; directing said drying gas toward said containers at high velocity using an associated directing device and in a plurality of closely spaced jets with the spacing between jets assuring that at least one jet is directed normally toward each of said containers; and circulating said drying gas against the bottom wall of each container, against and around its side wall, through said conveyor, and toward said control device; said circulating step enabling said flow control device and spaced jets to cooperate to assure each container is maintained in an upright manner with said drying gas being circulated around the outside thereof at high velocity to thereby provide efficient transfer of heat to the walls of each container and said circulating step also simultaneously enabling said flow control device and spaced jets to provide a negative pressure beneath each container and circulation of said drying gas within each container to provide said simultaneous drying.

2. A method as set forth in claim 1 and comprising the further step of introducing a dampening screen upstream of said directing device to reduce any turbulence in said drying gas.

3. A method as set forth in claim 1 in which said circulating step comprises circulating heated air.

4. A method as set forth in claim 1 in which said negative pressure is caused by a venturi effect upon circulating said drying gas over said containers and through said flow control device during said circulating step, said negative pressure ranging between roughly one-half inch and 2 inches of water which assures each of said containers is held in a stable upright manner while providing said simultaneous drying.

5. A method as set forth in claim 3 in which each bottom wall of each container has an outwardly concave depression defined therein, and comprising the further step of moving said containers from a washer in an inverted position with washing fluid contained in each depression and with at least one jet of air being directed normally toward each container the washing fluid is displaced from within its depression by the action of the associated jet of drying air while the associated container is maintained in an upright manner.

6. A method as set forth in claim 1 in which said drying gas comprises heated air and said circulating step comprises recirculating said heated air in a closed loop path while simultaneously heating the air downstream of said containers to dry any moisture picked up thereby due to drying of said containers whereby said recirculation enables said simultaneous drying in a more efficient and economical manner.

7. A method as set forth in claim 6 and comprising the further step of supporting a plurality of sets of screen and plate assemblies upstream of said directing device to reduce any turbulence in said heated air, each of said sets being defined by a perforated plate and an adjoining screen arranged upstream thereof with each screen being defined by a plurality of crisscrossed undulating wires. 

1. A method of simultaneously drying both the inside and outside of tubular containers each having a bottom wall and an adjoining side wall terminating in an end edge defining an open end; said method comprising the steps of; placing each of said containers in an inverted manner with its end edge resting on a horizontal portion of a perforated conveyor having a supporting surface and which allows substantially unobstructed flow of a drying gas therethrough in a direction perpendicular to its supporting surface; supporting a control device for said drying gas beneath said horizontal portion; said control device having a plurality of spaced apertures therein; directing said drying gas toward said containers at high velocity using an associated directing device and in a plurality of closely spaced jets with the spacing between jets assuring that at least one jet is directed normally toward each of said containers; and circulating said drying gas against the bottom wall of each container, against and around its side wall, through said conveyor, and toward said control device; said circulating step enabling said flow control device and spaced jets to cooperate to assure each container is maintained in an upright manner with said drying gas being circulated around the outside thereof at high velocity to thereby provide efficient transfer of heat to the walls of each container and said circulating step also simultaneously enabling said flow control device and spaced jets to provide a negative pressure beneath each container and circulation of said drying gas within each container to provide said simultaneous drying.
 2. A method as set forth in claim 1 and comprising the further step of introducing a dampening screen upstream of said directing device to reduce any turbulence in said drying gas.
 3. A method as set forth in claim 1 in which said circulating step comprises circulating heated air.
 4. A method as set forth in claim 1 in which said negative pressure is caused by a venturi effect upon circulating said drying gas over said containers and through said flow control device during said circulating step, said negative pressure ranging between roughly one-half inch and 2 inches of water which assures each of said containers is held in a stable upright manner while providing said simultaneous drying.
 5. A method as set forth in claim 3 in which each bottom wall of each container has an outwardly concave depression defined therein, and comprising the further step of moving said containers from a washer in an inverted position with washing fluid contained in each depression and with at least one jet of air being directed normally toward each container the washing fluid is displaced from within its depression by the action of the associated jet of drying air while the associated container is maintained in an upright manner.
 6. A method as set forth in claim 1 in which said drying gas Comprises heated air and said circulating step comprises recirculating said heated air in a closed loop path while simultaneously heating the air downstream of said containers to dry any moisture picked up thereby due to drying of said containers whereby said recirculation enables said simultaneous drying in a more efficient and economical manner.
 7. A method as set forth in claim 6 and comprising the further step of supporting a plurality of sets of screen and plate assemblies upstream of said directing device to reduce any turbulence in said heated air, each of said sets being defined by a perforated plate and an adjoining screen arranged upstream thereof with each screen being defined by a plurality of crisscrossed undulating wires. 